The present invention relates generally to a linkage assembly, and more particularly to a linkage assembly for connecting a work implement to a frame of a work machine.
Work machines, such as wheel loaders, typically include a linkage assembly which mechanically connects a work implement (e.g. a bucket) to a front end frame (herein after referred to as the xe2x80x9cframexe2x80x9d). The linkage assembly will typically include a slab lift arm or a box boom lift arm having one end thereof connected to the frame and the opposite end thereof coupled to the work implement. Generally, the linkage assembly also includes a number mechanical linkages and hydraulic cylinders coupled to the frame and the lift arm such that the lift arm, and therefore the work implement, can be moved relative to the frame. Movement of the lift arm and the work implement relative to the frame is necessary in order to do useful work with the work implement.
During operation of the work machine, the linkage assembly is subjected to various loads and forces, some of which may be severe. Therefore, it is critical that each component thereof has sufficient structure and connection to one another to provide the strength necessary to withstand these loads and forces. Heretofore, linkage assemblies have been constructed to be relatively large and bulky in order to accommodate the aforementioned forces. However, a drawback to these linkage assemblies is that they are so large and bulky that they tend to obstruct the view of an operator operating the work machine.
In addition, it should be understood that, on occasion, it is desirable to maintain the work implement at a predetermined angle relative to the ground while moving the lift arm to a raised position. Typically, linkage assemblies include additional mechanical and/or hydraulic mechanisms to maintain the work implement at the previously mentioned predetermined angle. However, a drawback to adding these additional mechanisms is that they increase the mechanical complexity, the expense, and the bulk of the linkage assembly.
What is needed therefore is a linkage assembly for connecting an implement to a frame of a work machine which overcomes one or more of the above-mentioned drawbacks.
In accordance with a first embodiment of the present invention, there is provided a linkage assembly for connecting an implement to a frame of a work machine. The linkage assembly includes a box-boom lift arm having a frame end portion and an implement end portion, wherein (i) the frame end portion is pivotally coupled to the frame, (ii) the implement end portion is pivotally coupled to the implement, and (iii) the frame end portion includes a first extension and a second extension spaced apart from each other so as to define a first lever space therebetween. The linkage assembly also-includes a lift cylinder having a frame end and a lift arm end, wherein (i) the frame end is pivotally coupled to the frame, and (ii) the lift arm end is pivotally coupled to the box boom lift arm. Moreover, the linkage assembly includes a rear tilt link having a first end and a second end, wherein the first end is pivotally coupled to the frame. The linkage assembly further includes a rear tilt lever having a cylinder end and a link end, wherein (i) the link end is pivotally coupled to the second end of the rear tilt link, (ii) the rear tilt lever is pivotally coupled to the box boom lift arm at a location which is interposed between the cylinder end and the link end, and (iii) the rear tilt lever extends through the first lever space. The linkage assembly also includes a tilt cylinder having a lever end and an implement end, wherein (i) the lever end is pivotally coupled to the cylinder end of the rear tilt lever, and (ii) the implement end is mechanically coupled to the implement.
In accordance with a second embodiment of the present invention, there is provided a linkage assembly for connecting an implement to a frame of a machine. The linkage assembly includes a lift arm having a frame end portion and an implement end portion, wherein (i) the frame end portion is pivotally coupled to the frame, (ii) the implement end portion is pivotally coupled to the implement, (iii) the lift arm includes an upper arm segment and a lower arm segment, and (iv) the upper arm segment includes a first extension and a second extension spaced apart from each other so as to define a first lever space therebetween. The linkage assembly also includes a lift cylinder having a frame end and a lift arm end, wherein (i) the frame end is pivotally coupled to the frame, and (ii) the lift arm end is pivotally coupled to the lift arm. Moreover, the linkage assembly includes a rear tilt lever having a cylinder end and a link end, wherein (i) the link end is mechanically coupled to the frame, (ii) the rear tilt lever is pivotally coupled to the lift arm at a location which is interposed between the cylinder end and the link end, and (iii) the rear tilt lever extends through the first lever space. The linkage assembly further includes a tilt cylinder having a lever end and an implement end, wherein (i) the lever end is pivotally coupled to the cylinder end of the rear tilt lever, and (ii) the implement end is mechanically coupled to the implement.